Bicycle Helmets
There are not many sports or activities that are likely to result in a fall on your head but bicycling has a serious exception. If you are in an accident that stops your bike suddenly your legs get brushed up as you go over the handlebars. This starts your body rotating and you have a good chance of landing headfirst.
When it happened to me on a downhill stretch at a high rate of speed, I went flipping over the handlebars and landed at the top (technically at that point the bottom) of my head. Both my helmet and my bike were toast. The top tube and the down tube of the bike were bent at a significant angle that I'd never seen in a bike frame before. All that was left of my helmet was a small piece on each end of the chinstrap, which was dangling from my glasses when I found them.
Landing on my head wasn't the end of my motion. I did take a serious beating with thumps. I did make it to work on time thanks to someone who saw it happen and offered me a ride. There was plenty of visible damage even after I cleaned off the blood. A woman at work said "Good morning" and I said "Good morning.....sort of," and she had a good laugh at that. It took a few days before I finally got the lenses in my glasses pointing in matching directions again.
I was really impressed that one part that wasn't at all sore was the top of my head. The helmet was in pieces, but in a really nice way that saved impact to my head. I don't know if that is a part of the design, but I am really thoroughly grateful that I was wearing it on that ride, as I usually do.
I certainly don't mind anyone else not wearing theirs, but I'm going to be wearing mine. I might not even have been wearing a helmet that day if I hadn't heard so many people talk about the importance of doing that and I did want to add my bit of experience.